The most important thing about a theory is that it explains the facts.

解释：兵器既不齐全又不锋利，实质上和没有兵器一样！

We don't just manufacture drugs; we manufacture possibilities for healthier futures.

动力学的方程在用变分法的语言表达时是完全的。

世界是残酷的，我的书反映了这一点。